Mystery of the dead Scottish seabirds. Is it bird flu?

Ms Morton said “There are theories about what’s going on, one being bird flu, the other a shortage of sand eels which are their food. But either way it feels pretty catastrophic, seeing so many dead birds. I’ve never really seen anything like it in the 30 years I’ve lived here.”

Numerous beach users, in both East Lothian and Fife have commented on the dead birds over social media, On the Lothian Birdwatch Facebook group a long thread of comments detailing dead birds, most of which were guillemots and razorbills.

A visitor to the beach at Seacliff reported having been shocked to find ten birds, washed up on the beach, which she identified as guillemot. Others reported unwell and dead guillemots at Edinburgh’s Newhaven, Aberlady, Musselburgh, Longniddry, Dunbar and also in Fife.

Another beachgoer observed: “At a beach in Fife, I estimated between 25 and 30 Guillemot. From young to adult. Some more decayed than others. I reported it to both the Scottish and UK Government departments for this.”

Many suspected bird flu. However, according to Dr Francis Daunt, seabird ecologist at the Centre for Ecology and Hydrology, testing has been done on some of the birds which suggests this is not the case.

“We’re following the event,” he said, “and some important, recent news is that a number of birds came back negative for avian flu, suggesting environmental conditions as the likely cause of this.”

Dr Daunt said: “That’s not to say that there isn’t avian flu, but it’s important because there might have been an assumption that it was avian flu. But we had suspected that the conditions were a factor, and those results support that.”

The current mass die-off of guillemots is reminiscent of a similar “big auk wreck” which took place in 2021, also involving over a thousand birds of the auk species.

The conclusion, following investigation, was that starvation was probably the main cause. The birds were emaciated. Many weighed half their normal body weight of just over a kilogram. Researchers at the Centre for Ecology and Hydrology later confirmed that the birds had indeed died of starvation.

Another theory was that the birds could have been poisoned by toxins from an algal bloom.

READ MORE: Avian flu ‘Wake-up’ call as fears rise for Scotland's seabirds

But one of the problems with working out likely cause is that these events can be multi-factorial, and it is hard to attribute one single reason.

When earlier this year there was concern over a relatively small number of guillemot deaths on Angelsey, one of the big questions was whether the anomalously high temperatures of June’s marine heatwave might be a factor in the deaths.

READ MORE: Guillemots. Mystery of the 1000 dead Scottish seabirds

READ MORE: Scotland's marine heatwave explained: from data to jellyfish

Dr Daunt pointed out at the time: “When we see deaths like these, there may not be one explanation. It may be that there are at least two things happening at once. And when wild birds, or any wild species are faced with multiple threats it can make matters even worse than adding the two together."

"So it may be that if there’s a marine heatwave and the quality of your food is going down, then your condition goes down and you are more susceptible to avian flu. And, similarly, if you‘ve had a disease and perhaps you’ve recovered from it, you may not be back to your tip-top self and may be more susceptible to a drop in food quality as a result of the marine heatwave.”

In Scotland this summer, testing has confirmed Highly Pathogenic Avian Influenza (HPAI) in Sandwich tern, common tern, kittiwake, herring gull, black-headed gull and guillemot.

Members of the public who find dead or sick birds are advised not to touch them and visitors to coastal areas are advised to keep their dogs on a lead to avoid them picking up dead birds. Dead wild birds should be reported on gov.uk's 'Report dead wild birds' page, or via the GB phone helpline: 03459 33 55 77.